Found out I was overpaying to ship cars because I kept booking last minute

So I used to always book my car shipment like 2 or 3 days before I needed it gone, thinking that was normal. I moved a Civic from Phoenix to Denver back in March and paid $1,150 for an open carrier, which felt steep but I just ate it. Then a dispatcher buddy of mine asked why I never gave more notice, and I was like what does that even change. He explained that brokers post loads on the board and carriers grab them based on routes they're already running, so if you give a week or two of lead time, you slot into a truck that's already heading that way instead of someone making a special trip. Next time I shipped a truck from Tucson to Boise I gave 10 days notice and paid $780 for the same kind of open transport. Same distance basically, same season, way less cash. Has anyone else messed around with their booking window and seen the price swing that much, or was this just me getting lucky with the timing?